Locking thread mechanism



Oct. 9, 1934. G. T HART, JR 1,976,017

LOCKING THREAD MECHANISM Filed Oct. 10, 1930 2 Sheets-Sheet Oct. 9,1934. G. T. HART, .JR 1,976,017

LOCKING THREAD MECHANISM Filed Oct. l0, 1930 2 Sheets-Sheet 2 PatentedOct. 9, 1934 LOCKING THREAD MECHANISM George T. Hart, Jr., Lynn, Mass.,assignor to` United Shoe Machinery Corporation, Paterson, N. J., acorporation of New Jersey Application October 1.0, 1930, Serial No.487,778 s claims. (ci. ira-22.3)

The present invention relates to the locking thread'mechanism oflockstitch sewing machines, and more particularly to the thread case andtenl, Y, sion devices of lockstitch shoe sewing machines employingrotary or oscillatory loop taking hooks or shuttles. Y

An object of the invention is to improve the locking Ythread mechanismof machines such as that illustrated and described in the patent toAshworth No. 1,169,909, dated February 1, 1916, for Sewingmachine, so asto adapt such machines to use a thread mass or cop which gives up threadfrom within rin place of the bobbin illustrated in Y said patent. Tothat end, a feature of the in vention consists of a thread case open atits Aforward. end for the reception of a thread cop and having formed inits rear surface a centrally located'thread'outlet. vA further objectofthe invention is to provide a thread tension device for oscillatory orrotary shuttles or thread cases which employ thread masses or cops whichgive up thread from within. Another object of the invention is toprovide a thread cop which will, of necessity, be positioned with itsproper surface adjacent the thread outlet of the thread case, andwhichis provided with a supporting casing to hold it against collapseduring the withdrawal of the last 7^few turns of,u thread on the cop,atwhich time a c op with no supporting medium tends to collapse. To`'theselenda the cop isrprovided with a casing of tin foil or likematerial about its periphery and 'uponthe surface opposite vthe threaddelivery end of the cop, andthe cop as 'thus encased is of such adiameter that it will `it closely within 'the'thread case, the close toft-he cop Within thethread case cooperating with the tin foil casingabout the cop to 4hold the cop against collapse. y

FurtherY objects of the invention are to provide a vthread tensiondevice which is simple, 'compact and durable and which enables a ineadjustment ofthe tension to be secured and in which .the parts arevsecurely `locked in adjusted position.V Y

With the above objects in View, thevinvention alsogconsists inthecombinations and arrangement of parts Vhereinafter described andclaimed,

the advantages of which will be obvious to those skilled in the art fromthe following description.

In the .accompanying drawings, illustrating the preferred form ci theinvention, Figure 1 is a plan v'view of the thread case with the tensionn device applied thereto; Figure 2 is a side View of the same; Figure 3is a sectional view taken on the line 3-3 of Figure 1; Figure 4 is adetail View of the tension adjusting device,` developed for convenienceof illustration; Figure 5 is a detail perspective view of the tensiondevice;v Figure 6 is a section on the line Y6--6 of Figure 1; and Figure7 is a sectional eleva-tion of a portion of the lockstitch sewingmachine illustrated and described in the patent to Ashworth hereinbeforereferred to having embodied thereinl the thread case and tension deviceof the present invention.

The body oi the thread case is cylindrical in form and comprises acircular vwall 8 closed at one end and open at the other end to receivethe thread cop. The iiange 10, extending partly 70 around the threadcase, is provided to engage in the supporting groove v11 in the innersurface of the rotary loop taking hook. `The thread outlet is indicatedat 12 and is centrally located in the thread case in order to adapt thesame to be 75 used in connection with thread cops. The tension devicescomprise a resilient thread engaging finger 14 positioned Within aradial opening formed in the thread caseand provided with a bevelledsurface 15 adapted to cooperate with the bevelled surface 16 formed inthe periphery of the thread outlet, said resilient member and bevelledsurface together forming a means for applying a yielding pressure to thethread as it passes through the thread outlet. The Vtension member 14 ispivot-ally mounted upon the convex surface 18 formed in the thread case,and is loosely held against longitudinal movement by the pin 20V mountedin said convex surface, which pin passes freely through a hole 21 in thetene sion member 14, suiiicient clearance being provided -between thepinl 20 and the periphery of the hole 21 to permit rocking movement ofthe tension member upon the convex surface 18. The tension member 14 is.turned up at its outer end and has the inclined surface 22 formed atthe extremity of the upturned portion thereof. Means for adjusting thethread tension consists of the inclined surface 24 `formed in themember26'. The inclined surface 24 is complementary to the inclined surface 22formed in the tension member 14 and is kadapted to slide upon saidsurface 22 in order to depress the outer end of the tension member 14,thereby increasing the pressure of the'tension member upon the thread.The member 26 is slidably -mounted '.lnfaconcentric dovetail grooveformed in the peripherypf'the thread case and is provided withbevelledsurfaces 28 adapted'to slide in said groove; ,It is obvious Vthat amovement of the member 26 in the direction of the arrow in Fig. 2 willdepress the outer end of the tension member lli and increase thepressure of said member upon the thread, and that a movement of themember 26 in the opposite direction will permit the outer end of tensionmember 14 to rise and thereby lessen the pressure of said member uponthe thread.

Means for locking the tension adjusting member 26 in adjusted positionconsists of a vertical projection 30 formed in one end thereof andadapted to engage alternatively a plurality of per-v forations 32 formedin the thread case. In or er to permit the tension adjustingmember 26 tobe unlocked and readjusted, the projection 30 is formed in a bifurcation34 formed in said member 26, the outer end of vsaid bifurcation having arecess or hole 36 formed therein for the reception of an unlocking tool.

The thread mass or thread cop is indicated at 38 in its proper positionwithin the thread oase and has the tin foil casing 40 pressed about itsperiphery and over the surface of the thread cop opposite the threaddelivery end thereof. By thus encasing the cop, the thread delivery endof the cop is clearly indicated and the operator must necessarilyposition the cop in the thread case with the thread delivery end thereofadjacent the thread outlet of the thread case, thereby preventing thetwisting and kinking of the locking thread which would result frommisplacing the thread cop.

The loop taker is indicated at 42 (see Fig. 7) and is in the form of atubular hook rotatably mounted upon the plates 44 and 46 secured to themachine frame, and adapted to support the thread case upon its innersurface, the thread case forming a closure for the rear end of the hook.The thread case is permanently mounted in the supporting groove l1 inthe hook and consequently the thread cop must be passed through theforward end of the hook and into the thread case. Motion is imparted tothe rotary hook 42 through the bevelled gear 48 which meshes with aseries of bevelled teeth cut in the periphery of the forward end of therotary hook. For a moreY complete description of the rotary hook and itsactuating mechanism, reference may be had to the patent to Ashworthhereinbefore referred to.

The nature and scope of the invention having been indicated and a deviceembodying the features thereof having been specically described, what isclaimed as the invention isz-- l. A locking thread mechanism for sewingmachines comprising a cylindrical thread case, a centrally locatedthread outlet in said case, a thread engaging surface at the peripheryof said outlet, a member adapted to compress the thread vagainst saidthread engaging surface,l andV means for imparting a Variable pressuretosaid member consisting of a member slidably mounted in the periphery ofthe thread case.

2. A locking thread mechanism for sewing machines comprising acylindrical thread case, a centrally located thread outlet Ain saidcase', a thread engaging surface at the periphery of said outlet, amember pivotally mounted in said case and adapted to compress the threadagainst said thread engaging surface, and means for imparting avariable'pressure to said member consisting of aV member slidablymounted in the periphery of the thread case.

3; A locking thread mechanism for sewing machines comprising acylindrical thread case, a centrally located thread outlet in said case,a thread engaging surface at the periphery of said outlet, a radiallypositioned member pivotally mounted in said case adapted to compress thethread against said thread engaging surface, and means for imparting aVariable pressure to said member consisting of a member slidably mountedin the periphery of the thread case.

4. A locking thread mechanism for sewing machines comprising acylindrical thread case, a centrally located thread outlet in said case,a thread engaging surface at the periphery of said outlet, a memberadapted to compress the thread 'against said thread engaging surface andmeans for imparting a variable pressure to said member consisting of amember slidably mounted in the periphery of the thread case, and meansfor locking said slidable member comprising a positioning surface formedin said member and adapted to co-act alternatively with a plurality ofpositioning surfaces formed in said thread case.

5. A locking thread mechanism for sewing machines comprising acylindrical thread case, a centrally located thread outlet in saidVcase, a thread engaging surface at the periphery of said outlet, amember adapted to compress the thread against said thread engagingsurface, and means for imparting a variable pressure tosaid memberconsisting of complementary, inter-engaging inclined surfaces, one ofsaid surfaces being formed in said member and the other being formed ina member slidably mounted in the periphery of the thread case.

6. A locking thread mechanism for sewing machines comprising acylindrical thread case, a centrally located thread outlet in'said case,a thread engaging surface at the periphery of said outlet, a memberadapted to compress the thread against said thread engaging surface andmeans for imparting a variable pressure to said member consisting of amember slidably mounted in the periphery of the thread case, and meansfor locking said slidable member comprising a projection formed in saidmember and adapted to engage alternatively a plurality of recessesformed in said thread case.

7. In a lockstitch sewing machine, the combination with an open endedtubular loop taker, of a stationary cylindrical thread case mounted insaid loop taker, said thread case being open at its forward end andclosed at its rear end to receive and hold tightly a threadcop passedthrough said loop'taker and into said thread case, means for holding thethread cop in proximity to the wall of the thread case until entirelyexhausted comprising an interlining of foil between the thread cop andthe thread case, a centrally located thread outlet in said thread case,and means for applying tension to the thread.

8. In a lockstitch sewing machine, the combination with an open endedtubular loop taker of a stationary cylindrical thread case mounted intheloop taker open at its forward end for the reception of a thread copinsertedl through the open end or" the loop taker, means for holding thethread cop in proximity to the wall of the thread case until entirelyexhausted comprising an interlining of foil between the thread cop andthe thread case arranged to leave the thread delivery end of thecop freeof foil, a centrally located thread outlet in said thread case throughwhich the thread passes from the'interior of the cop, and means forapplying tension to the thread. f

CxllOlftCiEv T. HART, JR.

